Convert between units of measurement (length, weight, temperature, area, volume, data storage) via @leehaohao/unit-converter-mcp (npx)

@leehaohao/unit-converter-mcp — verified execution recipe

Install & launch

npm install --prefix /tmp/unit-converter-mcp @leehaohao/unit-converter-mcp

Entry point: ./build/index.js (ESM module). Launch via MCP stdio transport.

macOS /tmp gotcha: resolve with realpath — /tmp → /private/tmp symlink breaks ESM import.meta.url guard.

Tools (12 total)

Key gotchas

1. Descriptions are in Chinese (Mandarin) — tool descriptions and parameter descriptions are all in Chinese, but the tool names, unit codes, and JSON output are English.
2. GB→MB uses 1024 (not 1000) — the server conflates SI prefixes (GB, MB, KB) with binary prefixes (GiB, MiB, KiB). Both 1 GB → MB and 1 GiB → MiB return 1024. This is technically incorrect per IEC 80000-13 (SI: 1 GB = 1000 MB), but matches common informal usage.
3. Temperature conversions are exact — 100°C → 212°F, 32°F → 0°C, 0K → -273.15°C all correct.
4. First call ~6ms JIT, rest ≤1ms.
5. Output is JSON object — {value, from_unit, to_unit, result}, result is a number (not string).
6. No speed/pressure/time/angle units — only the 6 categories above.

Verified trace (12 calls, 100% success, p50=1ms)

✓ [6ms] 1 mile → km: result=1.609344
✓ [6ms] 100 cm → in: result=39.370079
✓ [1ms] 1 kg → lb: result=2.204624
✓ [1ms] 16 oz → lb: result=1
✓ [1ms] 100°C → °F: result=212
✓ [1ms] 0K → °C: result=-273.15
✓ [1ms] 32°F → °C: result=0
✓ [1ms] 1 acre → m²: result=4046.86
✓ [1ms] 1 gallon → liters: result=3.78541
✓ [0ms] 1 GB → MB: result=1024
✓ [0ms] 1 GiB → MiB: result=1024
✓ [1ms] list_length_units: ["m","km","cm","mm","in","ft","yd","mi"]